The project

NEMSIC's objective is to develop a new generation of smart sensors and actuators for gases and biological substances particularly suited for monitoring of critical environment and for genetics, pharmacology and drug discovery. NEMSIC envisions to integrate solid-state semiconductor micro/nano devices and micro/nano mechanical devices in a single chip for new functionalities and increased performances. In the last decade the research for the development of microelectronics devices has evolved towards miniaturization to the scale of nanometre (10-9 meter) and also towards the use of new silicon substrates like silicon on insulator (SOI), today widely adopted, and silicon on nothing (SON, which is a procedure for creating locally silicon membranes suspended over an etched area which can eventually be filled with an appropriate material or left in air). On the other side micro mechanical systems (MEMS) have also evolved in the direction of nanoscale (NEMS) but have gained reliability and maturity. However, up to now a true hybrid of NEMS devices and of microelectronics has never been demonstrated. NEMSIC intends to explore this new direction with the objective to discover the necessary technologies for tomorrow’s smart sensors based applications.

For NEMSIC a “smart sensor” is an advanced sensing element with selectivity to a particular type of stimulus among similar ones, e.g. a CO2 molecule among O2 and others. The smart sensor is based on a sensing component that has gained selectivity thanks to a special treatment called functionalization. In addition, NEMSIC sets the target for integration of the “smart sensors” with CMOS technology, a step that by the end of the project will give an added nuance to the term “smart” as it will render possible to have the circuitry for the diagnostics and the storage of the data on the same substrate as the sensors.

Figure 1 Transistor with suspended vertical vibrating gate.

The technological challenges that NEMSIC is going to address are double:- the demonstration of a fabrication platform on silicon or on SOI for vibrating and switchable NEM structures with feature size smaller than 100 nanometers that will enable sensing performances and miniaturisation beyond any actual system and - the compatibility of this platform with standard electronics.In the beginning the project will develop new principles and key technologies for NEMS smart sensing systems for monitoring and controlling chemical species in the environment and for detecting specific biomolecules. First a breakthrough of the technological requirements from the applications end users will be performed, then novel NEMS sensing designs will be analyzed, together with techniques for immobilizing chemical species and biomolecules; in parallel hybrid models and simulation tools will be developed to support the technology.One of the core activities of the project consists in the realization of NEMS for the power management of smart systems; in fact for meeting a rapid increase in demands for extending the lifetime of smart sensors, novel power management technologies are required including ultra-low-power circuit technologies and those combined with self-power generation techniques. The project consortium will use substantial efforts to provide NEMS circuits for this purpose and the suspended gate transistor (SGFET) shown in figure 1 has been chosen as a very promising candidate.

Figure 2 suspended silicon nanowire
with sub-50nm cross section.

The second core activity of the project is the study of co-design and compatibility for the NEM devices with the readout electronics. Circuits especially conceived for the reading of the sensing values will be developed in two fabrication processes, allowing for optimization of the characteristics measured in the first run. Also great attention will be given to reliability and metrology of both NEMS and electronics circuits.In parallel NEMSIC will develop a technology platform that will allow for the fabrication of advanced NEMS. This technology once achieved will serve the results obtained in the main project activities for the realization of sensing, power management and electronic circuits.

A very advanced technology will be developed by the project especially concerning the scaling, which will reach a feature size of 50 nanometres or less. In figure 2 an example of such extremely small feature size is shown in a typical suspended nanowire, which can show excellent performances in terms of sensitivity, stiffness and in miniaturization, in addition to the high frequency vibration capability.Figure 2, shows also a possible architecture of an electrostatically actuated suspended nanowire that can be realized with the technology provided by the project partners. The successful achievement of the NEMSIC goals will allow to functionalize such nano structures to become sensible to certain measurable quantities like gases and biological sample as well as to combine them with the appropriate electronics for powering, reading and storing.